1. Field of the Invention
The present invention relates to vehicle suspension systems and more particularly to a vehicle suspension system for reducing roll tendency in a moving vehicle.
2. Description of the Prior Art
Rotational stability in vehicle dynamics involves constraint of the vehicle frame about the longitudinal axis of the vehicle relative to the plane containing the axle system. The plane containing the frame has a tendency to rotate about the roll center of the vehicle while the axle plane is generally treated as a fixed horizontal plane in discussions involving vehicle roll characteristics.
The externally applied force that produces roll is generated by curvilinear motion of the vehicle in the longitudinal direction. It is treated as a horizontal force acting at the vehicle's center of gravity and parallel to the axle plane. Under the influence of this force, the axle-plane and frame-plane converge and diverge imparting a rolling motion to the vehicle which generally creates adverse ride conditions on passengers and cargo.
Resistance to roll is commonly controlled by component forces of the suspension system which react unidirectionally and singly on the converging side of the vehicle. In conventional air suspension systems, as the vehicle rolls, the springs and torque arms on the converging side react to achieve equilibrium while the springs on the diverging side react in the roll direction, contributing to roll displacement.
In vehicle systems requiring high ride quality, suspension springs of low rate-high deflection are employed. However, this arrangement produces adverse roll stability involving high degrees of rotational displacement.